Information Notice 1991-29, Deficiencies Identifie During Electrical Distribution System Functional Inspections: Difference between revisions

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| issue date = 04/15/1991
| issue date = 04/15/1991
| title = Deficiencies Identifie During Electrical Distribution System Functional Inspections
| title = Deficiencies Identifie During Electrical Distribution System Functional Inspections
| author name = Rossi C E
| author name = Rossi C
| author affiliation = NRC/NRR
| author affiliation = NRC/NRR
| addressee name =  
| addressee name =  
Line 14: Line 14:
| page count = 10
| page count = 10
}}
}}
{{#Wiki_filter:4 A UNITED STATES NUCLEAR REGULATORY
{{#Wiki_filter:4 A


COMMISSION
===UNITED STATES===
NUCLEAR REGULATORY COMMISSION


===OFFICE OF NUCLEAR REACTOR REGULATION===
===OFFICE OF NUCLEAR REACTOR REGULATION===
WASHINGTON, D.C. 20555 April 15, 1991 NRC INFORMATION
WASHINGTON, D.C.


NOTICE NO. 91-29: DEFICIENCIES
20555


IDENTIFIED
===April 15, 1991===
NRC INFORMATION NOTICE NO. 91-29:


===DURING ELECTRICAL===
===DEFICIENCIES IDENTIFIED DURING ELECTRICAL===
DISTRIBUTION
DISTRIBUTION SYSTEM FUNCTIONAL INSPECTIONS
 
SYSTEM FUNCTIONAL
 
INSPECTIONS


==Addressees==
==Addressees==
:
:
All holders of operating
All holders of operating licenses or construction permits for nuclear power
 
licenses or construction


permits for nuclear power reactors.
reactors.


==Purpose==
==Purpose==
: This information
:
 
This information notice is intended to alert addressees to deficiencies identi- fied during recently performed electrical distribution system functional
notice is intended to alert addressees
 
to deficiencies
 
identi-fied during recently performed
 
electrical
 
distribution
 
system functional


inspections (EDSFIs).
inspections (EDSFIs).


It is expected that recipients
It is expected that recipients will review the informa- tion for applicability to their facilities and consider actions, as appropri- ate, to avoid similar problems.


will review the informa-tion for applicability
===However, suggestions contained in this===
information notice do not constitute NRC requirements; therefore, no specific


to their facilities
action or written response is required.


and consider actions, as appropri-ate, to avoid similar problems.
==Description of Circumstances==
 
:
However, suggestions
During multidisciplinary inspections, the U.S. Nuclear Regulatory Commission
 
contained
 
in this information
 
notice do not constitute
 
NRC requirements;
therefore, no specific action or written response is required.Description
 
of Circumstances:
During multidisciplinary
 
inspections, the U.S. Nuclear Regulatory
 
Commission (NRC) has identified
 
many deficiencies
 
related to tWeelectrical
 
distribution
 
system. To address these deficiencies, the NRC has developed
 
an inspection
 
to specifically
 
evaluate the electrical
 
distribution
 
system. During the last year, the NRC completed
 
eight EDSFIs, performing


at least one in each of the five NRC geographical
(NRC) has identified many deficiencies related to tWeelectrical distribution


regions. During these inspections, the staff found several common deficiencies
system. To address these deficiencies, the NRC has developed an inspection to


in the licensees'
specifically evaluate the electrical distribution system. During the last
programs and in the electrical


distribution
year, the NRC completed eight EDSFIs, performing at least one in each of the


systems as designed and configured
five NRC geographical regions. During these inspections, the staff found


at each plant. These deficien-cies included inadequate
several common deficiencies in the licensees' programs and in the electrical


ac voltages at the 480 Vac and 120 Vac distribution
distribution systems as designed and configured at each plant. These deficien- cies included inadequate ac voltages at the 480 Vac and 120 Vac distribution


levels, inadequate
levels, inadequate procedures to test circuit breakers, and inadequate determi- nations and evaluations of setpoints.
 
procedures
 
to test circuit breakers, and inadequate
 
determi-nations and evaluations
 
of setpoints.


Discussion:
Discussion:
Inadequate
Voltage During inspections
conducted
at the San Onofre Nuclear Generating
Station (Inspection
Reports 50-361/89-200
and 50-362/89-200), the Susquehanna
Steam Electric Station (Inspection
Reports 50-387/90-200
and 50-388/90-200), and the 9104090124
' J IN 91-29 April 15, 1991 Waterford
Steam Electric Station (Inspection
Report 50-382/90-23), the staff found that, under certain conditions, the voltage available


at the safety buses would be inadequate
===Inadequate Voltage===
During inspections conducted at the San Onofre Nuclear Generating Station


to Operate safety-related
(Inspection Reports 50-361/89-200 and 50-362/89-200), the Susquehanna Steam


loads and associated
Electric Station (Inspection Reports 50-387/90-200 and 50-388/90-200), and the


equipment.
9104090124


These conditions
' J


could occur when the plan~t's electrical
IN 91-29 April 15, 1991 Waterford Steam Electric Station (Inspection Report 50-382/90-23), the staff


distribution
found that, under certain conditions, the voltage available at the safety buses


systems were being supplied from an offsite grid that had become degraded but that continued
would be inadequate to Operate safety-related loads and associated equipment.


to supply voltages that remained above the setpoints
These conditions could occur when the plan~t's electrical distribution systems


at which the degraded grid relays would be activated.
were being supplied from an offsite grid that had become degraded but that


At San Onofre, the numerous voltage drops throughout
continued to supply voltages that remained above the setpoints at which the


the system could cause the voltage to 120 Vaciontactors
degraded grid relays would be activated.


to drop below the-voltage
At San Onofre, the numerous voltage drops throughout the system could cause the


range for which these contactors
voltage to 120 Vaciontactors to drop below the-voltage range for which these


were certified
contactors were certified as acceptable by their manufacturers.


as acceptable
To resolve


by their manufacturers.
this problem the licensee has performed testing that established a lower


To resolve this problem the licensee has performed
acceptable voltage range for this equipment.


testing that established
At Susquehanna, the degraded grid relay setpoint'was'set at 84 percent on the


a lower acceptable
4160 Yac buses.


voltage range for this equipment.
Th'i's setpoint could have allowed inadequate voltage to be


At Susquehanna, the degraded grid relay setpoint'was'set
-delivered to numerous safety-related loads at both the 480 Vac and 120 Vac


at 84 percent on the 4160 Yac buses. Th'i's setpoint could have allowed inadequate
levels. The licensee calculated that setpoints'of at least 93 percent would be


voltage to be-delivered
required to ensure adequate voTtage to all safety-related equipment. To


to numerous safety-related
resolve this problem, the lice'isee has raised the setpoints of the degraded


loads at both the 480 Vac and 120 Vac levels. The licensee calculated
grid relays and has initiated a modification to install 120 Vac regulating
 
that setpoints'of
 
at least 93 percent would be required to ensure adequate voTtage to all safety-related
 
equipment.
 
To resolve this problem, the lice'isee
 
has raised the setpoints
 
of the degraded grid relays and has initiated
 
a modification
 
to install 120 Vac regulating


transformers.
transformers.


At the Waterford
At the Waterford nuclear plant, the degraded grid relays were set at


nuclear plant, the degraded grid relays were set at 87.5 percent'as
87.5 percent'as sensed on the'4160 Vac buses. :Although this setting was found


sensed on the'4160 Vac buses. :Although
to be marginally adequate-'for-equipment connected to the 4160 Vac buses, the


this setting was found to be marginally
setting was too low to ensure that adequate v6ltage would'be maintained at the


adequate-'for-equipment
480 Vac and 120 Vac levels. The licensee is 6e4aluating solutions to this


connected
problem and has instituted a procedure- to manually'separate from the grid if


to the 4160 Vac buses, the setting was too low to ensure that adequate v6ltage would'be maintained
the voltage falls to unacceptable levels but remains above the relay setpoints.


at the 480 Vac and 120 Vac levels. The licensee is 6e4aluating
The function of the degraded grid relays is to en'sure that adequate voltage is


solutions
available tooperate all Class lE loads at all distribution levels.


to this problem and has instituted
In order


a procedure- to manually'separate
to ensure-that all required' Class E 'loads will remain operable during degraded


from the grid if the voltage falls to unacceptable
voltage conditions, some licensees are currently'reanalyzing the basis for the


levels but remains above the relay setpoints.
degraded grid relay setpoints. The new analyses consider all required Class 1E


The function of the degraded grid relays is to en'sure that adequate voltage is available
loads and include the assumption that the voltage on the buses being sensed by


tooperate
these relays can remain at a level just above the relay setpoints.


all Class lE loads at all distribution
===Inadequate Circuit Breaker Testing Procedures===
During recent EDSFIs ahd previously on other NRC inspections, the staff identi- fied repetitive deficiencies in licensees' programs to test circuit breakers.


levels. In order to ensure-that
These deficiencies included inadequate procedures, inadequate test acceptance


all required'
criteria, inadequate test equipment, and inadequate control of testing. At the
Class E 'loads will remain operable during degraded voltage conditions, some licensees


are currently'reanalyzing
Susquehanna plant (Inspection Reports 50-387/90-200 and 50-388/90-200), the


the basis for the degraded grid relay setpoints.
staff found that the licensee was testing dc molded case circuit breakers with


The new analyses consider all required Class 1E loads and include the assumption
a procedure written for testing ac breakers. The licensee had not established


that the voltage on the buses being sensed by these relays can remain at a level just above the relay setpoints.
specific acceptance criteria for the dc breakers.


Inadequate
IN 91-29 April 15, 1991 At the Shearon Harris Nuclear Power Plant (Inspection Report 50-400/90-200),
the staff identified that the licensee was.testing molded case circuit breakers


===Circuit Breaker Testing Procedures===
against National Electrical Manufacturers Association (NEMA),acceptance crite- ria, which were less stringent than the manufacturer's time-current curves for
During recent EDSFIs ahd previously


on other NRC inspections, the staff identi-fied repetitive
these breakers. In addition, the staff identified that the licensee was


deficiencies
testing 480 V air circuit breakers with test equipment that applied a test


in licensees'
signal (secondary injection) to the solid state trip units in the circuit
programs to test circuit breakers.These deficiencies


included inadequate
breakers.


procedures, inadequate
Although this method adequately verified that the trip units func- tioned properly, it did not verify that the breaker's current transformer


test acceptance
functioned properly or that the wiring and connectors were adequate between the


criteria, inadequate
current transformer and the solid state trip units. Other licensees have


test equipment, and inadequate
performed testing by primary current injection or by individually checking each


control of testing. At the Susquehanna
component of the circuit breaker, including the wiring and connectors to


plant (Inspection
demonstrate that the circuit breaker functions properly.


Reports 50-387/90-200
Inadequate Determinations and Evaluations of Setpoints
and 50-388/90-200), the staff found that the licensee was testing dc molded case circuit breakers with a procedure


written for testing ac breakers.
Many of the findings identified during recent EDSFIs were related to inadequate


===The licensee had not established===
setpoint determinations. Useful guidance for determining setpoints is provided
specific acceptance


criteria for the dc breakers.
by Instrument Society of America Standard 67.04-1982, "Setpoints for Nuclear


IN 91-29 April 15, 1991 At the Shearon Harris Nuclear Power Plant (Inspection
Safety-Related Instrumentation used in Nuclear Power Plants," which the NRC


Report 50-400/90-200), the staff identified
staff has endorsed by Regulatory Guide 1.105 Revision 2 -
1986, "Instrument


that the licensee was.testing
Setpoints for Safety-Related Systems." This guidance applies both to process


molded case circuit breakers against National Electrical
instrumentation and, in part, to certain relays that perform a safety function.


Manufacturers
Some licensees have operated equipment outside of acceptable limits because


Association (NEMA),acceptance
they did not determine proper setpoints and did not evaluate and account for


crite-ria, which were less stringent
instrument drift. Operating the equipment under these conditions could


than the manufacturer's
compromise the safety functions of the equipment. The staff has identified


time-current
these circumstances primarily for those instruments in which the licensee has


curves for these breakers.
determined the setpoints as opposed to those instruments for which the


In addition, the staff identified
setpoints were determined by the architect/engineer or the nuclear safety


that the licensee was testing 480 V air circuit breakers with test equipment
system supplier. Those setpoints not contained in the plant technical specifi- cations were also more frequently found to be deficient. During recent EDSFIs, the staff identified deficiencies in setpoints for diesel day tank level


that applied a test signal (secondary
indicators, diesel air start compressor controllers and alarms, inverter low


injection)
voltage shutdown circuitry, degraded grid relays, and diesel overcurrent
to the solid state trip units in the circuit breakers.


Although this method adequately
relays.


verified that the trip units func-tioned properly, it did not verify that the breaker's
In addition to identifying deficiencies in the setpoints themselves, the NRC


current transformer
has determined that not all the licensees are typically verifying that the


functioned
magnitude of instrument drift that was assumed in the original setpoint calcu- lation coincides with the magnitude of drift observed in the plant. Some


properly or that the wiring and connectors
licensees have corrected this deficiency by verifying the magnitude of instru- ment drift by trending, (comparing "as found" calibration data to previous "as


were adequate between the current transformer
left" data). This is particularly important for the degraded grid relay


and the solid state trip units. Other licensees
setpoints, which often require very tight calibration tolerance bands, and for


have performed
which very low drift values are often assumed.


testing by primary current injection
v- IN 91-29 April 15, 1991 This information notice requires no specific action or written response. If


or by individually
you have any questions about the information in this notice, please contact the


checking each component
technical contact listed below or the appropriate NRR project manager.


of the circuit breaker, including
===Charles E. Rossi, eirector===
Division of Operational Events Assessment


the wiring and connectors
===Office of Nuclear Reactor Regulation===


to demonstrate
===Technical Contact:===


that the circuit breaker functions
===Jeffrey B. Jacobson, NRR===
(301) 492-0996 Attachment: List of Recently Issued NRC Information Notices


properly.Inadequate
i


Determinations
===Attachment 1===
IN 91-29


and Evaluations
===April 15, 1991 LIST OF RECENTLY ISSUED===
NRC INFORMATION NOTICES


of Setpoints Many of the findings identified
Information


during recent EDSFIs were related to inadequate
Date of


setpoint determinations.
Notice No.


Useful guidance for determining
Subject


setpoints
Issuance


is provided by Instrument
Issued to


Society of America Standard 67.04-1982, "Setpoints
91-28
91-27
89-90,
Supp. 1
91-26
91-25
91-24
91-23


for Nuclear Safety-Related
===Cracking in Feedwater===
System Piping


Instrumentation
===Incorrect Rotation of===
Positive Displacement Pump


used in Nuclear Power Plants," which the NRC staff has endorsed by Regulatory
===Pressurizer Safety Valve===
Lift Setpoint Shift


Guide 1.105 Revision 2 -1986, "Instrument
===Potential Nonconservative===
Errors in the Working Format


Setpoints
Hansen-Roach Cross-Section


for Safety-Related
===Set Provided with The Keno===
and Scale Codes


Systems." This guidance applies both to process instrumentation
Commercial-Grade Structural


and, in part, to certain relays that perform a safety function.Some licensees
===Framing Components Supplied===
As Nuclear Safety-Related


have operated equipment
Equipment


outside of acceptable
===Recent Operating Experience===
Involving Reactor Operation


limits because they did not determine
===Without A Licensed Reactor===
Operator or Senior Reactor


proper setpoints
===Operator Present in the===
Control Room


and did not evaluate and account for instrument
Accidental Radiation Over- exposures to Personnel Due to


drift. Operating
Industrial Radiography Acces- sory Equipment Malfunctions


the equipment
04/15/91


under these conditions
===All holders of OLs or===
CPs for pressurized


could compromise
water reactors (PWRs).


the safety functions
04/10/91


of the equipment.
===All holders of OLs or===
CPs for nuclear power


===The staff has identified===
reactors.
these circumstances


primarily
04/10/91


for those instruments
===All holders of OLs or===
CPs for nuclear power


in which the licensee has determined
reactors.


the setpoints
04/02/91


as opposed to those instruments
===All fuel cycle licensees===
and other licensees, in- cluding all holders of


for which the setpoints
operating licenses for


were determined
nuclear power reactors, who use physics codes to


by the architect/engineer
support criticality


or the nuclear safety system supplier.
safety in the use of


Those setpoints
fissile material.


not contained
04/01/91


in the plant technical
===All holders of OLs or===
CPs for nuclear power


specifi-cations were also more frequently
reactors.


found to be deficient.
03/26/91


During recent EDSFIs, the staff identified
===All holders of OLs or===
CPs for nuclear power, test, and research re- actors, and all Part 55 licensed operators.


deficiencies
03/26/91


in setpoints
===All Nuclear Regulatory===
Commission (NRC) licens- ees authorized to use


for diesel day tank level indicators, diesel air start compressor
sealed sources for indus- trial radiography.


controllers
OL = Operating License


and alarms, inverter low voltage shutdown circuitry, degraded grid relays, and diesel overcurrent
CP = Construction Permit


relays.In addition to identifying
IN 91-29 April 15, 1991 This information notice requires no specific action or written response. If


deficiencies
you have any questions about the information in this notice, please contact the


in the setpoints
technical contact listed below or the appropriate NRR project manager.


themselves, the NRC has determined
O6ginal agen& by


that not all the licensees
Charles E. Ross!


are typically
===Charles E. Rossi, Director===
Division of Operational Events Assessment


verifying
===Office of Nuclear Reactor Regulation===


that the magnitude
===Technical Contact:===


of instrument
===Jeffrey B. Jacobson, NRR===
(301) 492-0996 Attachment:


drift that was assumed in the original setpoint calcu-lation coincides
===List of Recently Issued NRC Information Notices===
*SEE PREVIOUS


with the magnitude
04/ fI9 OGC :DOEA: RR


of drift observed in the plant. Some licensees
PCWen


have corrected
04/
/91


this deficiency
===CONCURRENCES===
*C/OGCB:DOEA:NRR*RPB:ADM


by verifying
*C/SICB:DST:NRR


the magnitude
CHBerlinger


of instru-ment drift by trending, (comparing "as found" calibration
TechEd


data to previous "as left" data). This is particularly
SNewberry


important
04/08/91
03/20/91
03/18/91
*RSIB:DRIS:NRR *SC/RSIB:DRIS:NRR*C/RSIB:DRIS:NRR


for the degraded grid relay setpoints, which often require very tight calibration
JBJacobson:bt
 
tolerance
 
bands, and for which very low drift values are often assumed.
 
v-IN 91-29 April 15, 1991 This information
 
notice requires no specific action or written response.
 
If you have any questions
 
about the information
 
in this notice, please contact the technical
 
contact listed below or the appropriate
 
NRR project manager.Charles E. Rossi, eirector Division of Operational
 
===Events Assessment===
Office of Nuclear Reactor Regulation
 
Technical
 
Contact: Jeffrey B. Jacobson, NRR (301) 492-0996 Attachment:
List of Recently Issued NRC Information
 
Notices i
 
Attachment
 
1 IN 91-29 April 15, 1991 LIST OF RECENTLY ISSUED NRC INFORMATION
 
NOTICES Information
 
Date of Notice No. Subject Issuance Issued to 91-28 91-27 89-90, Supp. 1 91-26 91-25 91-24 91-23 Cracking in Feedwater System Piping Incorrect
 
Rotation of Positive Displacement
 
Pump Pressurizer
 
Safety Valve Lift Setpoint Shift Potential
 
===Nonconservative===
Errors in the Working Format Hansen-Roach
 
Cross-Section
 
Set Provided with The Keno and Scale Codes Commercial-Grade
 
Structural
 
Framing Components
 
Supplied As Nuclear Safety-Related
 
Equipment Recent Operating
 
Experience
 
Involving
 
Reactor Operation Without A Licensed Reactor Operator or Senior Reactor Operator Present in the Control Room Accidental
 
Radiation
 
Over-exposures
 
to Personnel
 
Due to Industrial
 
Radiography
 
Acces-sory Equipment
 
===Malfunctions===
04/15/91 All holders of OLs or CPs for pressurized
 
water reactors (PWRs).04/10/91 All holders of OLs or CPs for nuclear power reactors.04/10/91 All holders of OLs or CPs for nuclear power reactors.04/02/91 All fuel cycle licensees and other licensees, in-cluding all holders of operating
 
licenses for nuclear power reactors, who use physics codes to support criticality
 
safety in the use of fissile material.04/01/91 All holders of OLs or CPs for nuclear power reactors.03/26/91 All holders of OLs or CPs for nuclear power, test, and research re-actors, and all Part 55 licensed operators.
 
03/26/91 All Nuclear Regulatory
 
Commission (NRC) licens-ees authorized
 
to use sealed sources for indus-trial radiography.
 
OL = Operating
 
License CP = Construction
 
Permit
 
IN 91-29 April 15, 1991 This information
 
notice requires no specific action or written response.
 
If you have any questions
 
about the information
 
in this notice, please contact the technical
 
contact listed below or the appropriate
 
NRR project manager.O6ginal agen& by Charles E. Ross!Charles E. Rossi, Director Division of Operational


===Events Assessment===
EVImbro
Office of Nuclear Reactor Regulation


Technical
WDLanning


Contact: Jeffrey B. Jacobson, NRR (301) 492-0996 Attachment:
02/08/91
List of Recently Issued NRC Information
02/08/91
02/19/91
*C/SELB:DST:NRR


Notices*SEE PREVIOUS 04/ fI9 OGC :DOEA: RR PCWen 04/ /91 CONCURRENCES
FRosa
 
*C/OGCB:DOEA:NRR*RPB:ADM
 
*C/SICB:DST:NRR
 
CHBerlinger
 
TechEd SNewberry 04/08/91 03/20/91 03/18/91*RSIB:DRIS:NRR
 
*SC/RSIB:DRIS:NRR*C/RSIB:DRIS:NRR
 
JBJacobson:bt


EVImbro WDLanning 02/08/91 02/08/91 02/19/91*C/SELB:DST:NRR
03/18/91
*D/DRIS:NRR


FRosa 03/18/91*D/DRIS:NRR
BKGrimes


BKGrimes 02/27/91  
02/27/91
*- I IN 91-XX April xx, 1991 This information


notice requires no specific action or written response.
*- I


If you have any questions
IN 91-XX


about the information
April xx, 1991 This information notice requires no specific action or written response. If


in this notice, please contact the technical
you have any questions about the information in this notice, please contact the


contact listed below or the appropriate
technical contact listed below or the appropriate NRR project manager.


NRR project manager.Charles E. Rossi, Director Division of Operational
===Charles E. Rossi, Director===
Division of Operational Events Assessment


===Events Assessment===
===Office of Nuclear Reactor Regulation===
Office of Nuclear Reactor Regulation


Technical
===Technical Contact:===


Contact: Jeffrey B. Jacobson, NRR (301) 492-0996 List of Recently Issued NRC Information
===Jeffrey B. Jacobson, NRR===
(301) 492-0996


Notices Attachment:
===List of Recently Issued NRC Information Notices===
Attachment:
*SEE PREVIOUS CONCURRENCES
*SEE PREVIOUS CONCURRENCES


Line 670: Line 486:
C/OGCB:DO
C/OGCB:DO


T*RPB:Ad SNewBerry CERossi Y- CHBerling
T*RPB:Ad


rjw TechEd 04/ /91 04/8/91 03/20/91 03/18/91 ,c CB:DOEA:NRR
SNewBerry


*RSIB:DRIS:NRR
CERossi Y-


*SC/RSIB:DRIS:NRR*C/RSIB:DRISNRR
===CHBerling rjw TechEd===
04/ /91
04/8/91
03/20/91
03/18/91
,c


4CvPvWen JBJacobson:bt
CB:DOEA:NRR *RSIB:DRIS:NRR *SC/RSIB:DRIS:NRR*C/RSIB:DRISNRR


EVImbro WMLanning 04/cl/91 02/08/91 02/08/91 02/19/91*C/SELB:DST:NRR
4CvPvWen


FRosa 03/18/91*D/DRIS:NRR
JBJacobson:bt


BKGrimes 02/27/91 IN 91-XX March xx, 1991 Inadequate
EVImbro


Determinations
WMLanning


and Evaluations
04/cl/91
02/08/91
02/08/91
02/19/91
*C/SELB:DST:NRR


of Setpoints Many of the findings identified
FRosa


during recent EDSFIs related to inadequate
03/18/91
*D/DRIS:NRR


setpoint determinations.
BKGrimes


Useful guidance for determining
02/27/91


setpoints
IN 91-XX


is provided by Instrument
March xx, 1991 Inadequate Determinations and Evaluations of Setpoints


Society of America Standard 67.04-1982, "Setpoints
Many of the findings identified during recent EDSFIs related to inadequate


for Nuclear Safety-Related
setpoint determinations. Useful guidance for determining setpoints is provided


Instrumentation
by Instrument Society of America Standard 67.04-1982, "Setpoints for Nuclear


used in Nuclear Power Plants," which the NRC staff has endorsed by Regulatory
Safety-Related Instrumentation used in Nuclear Power Plants," which the NRC


Guide 1.105 Revision 2 -1986, "Instrument
staff has endorsed by Regulatory Guide 1.105 Revision 2 - 1986, "Instrument


Setpoints
Setpoints for Safety-Related Systems." This guidance applies both to process


for Safety-Related
instrumentation and, in part, to certain relays that perform a safety function.


Systems." This guidance applies both to process instrumentation
Licensees have operated equipment outside of acceptable limits because they did


and, in part, to certain relays that perform a safety function.Licensees
not determine proper setpoints and did not evaluate and account for instrument


have operated equipment
drifts. Operating the equipment under these conditions could compromise the


outside of acceptable
safety functions of the equipment. The staff has identified these circum- stances primarily for those instruments in which the licensee has determined


limits because they did not determine
the setpoints as opposed to those instruments for which the setpoints were


proper setpoints
determined by the architect/engineer or the nuclear safety system supplier.


and did not evaluate and account for instrument
Those setpoints not contained in the plant technical specifications were also


drifts. Operating
more frequently found to be deficient. During recent EDSFIs, the staff


the equipment
identified deficiencies in setpoints for diesel day tank level indicators, diesel air start compressor controllers and alarms, inverter low voltage


under these conditions
shutdown circuitry, degraded grid relays, and diesel overcurrent relays.


could compromise
In addition to identifying deficiencies in the setpoints themselves, the NRC


the safety functions
has determined that licensees are not typically verifying that the magnitude


of the equipment.
of instrument drift that was assumed in the original setpoint calculation


The staff has identified
coincides with the magnitude of drift observed in the plant.


these circum-stances primarily
===Licensee can===
verify the magnitude of instrument drift by trending, (comparing 'as found"
calibration data to previous 'as left" data). This is particularly important


for those instruments
for the degraded grid relay setpoints, which often require very tight calibra- tion tolerance bands, and for which very low drift values are often assumed.


in which the licensee has determined
This information notice requires no specific action or written response. If


the setpoints
you have any questions about the information in this notice, please contact the


as opposed to those instruments
technical contact listed below or the appropriate NRR project manager.


for which the setpoints
===Charles E. Rossi, Director===
Division of Operational Events Assessment


were determined
===Office of Nuclear Reactor Regulation===


by the architect/engineer
===Technical Contact:===


or the nuclear safety system supplier.Those setpoints
===Jeffrey B. Jacobson, NRR===
(301) 492-0996 Attachment:
RPB:ADM


not contained
TechEd* imJa


in the plant technical
03/20/91 P


specifications
RSIB:DRIS


were also more frequently
JBdacobson*:t


found to be deficient.
02/08/91


During recent EDSFIs, the staff identified
===List of Recently Issued NRC Information Notices===
C:OGCB:UOEA


deficiencies
D:DOEA


in setpoints
*See previous c


for diesel day tank level indicators, diesel air start compressor
CHBerlinger


controllers
CERossi


and alarms, inverter low voltage shutdown circuitry, degraded grid relays, and diesel overcurrent
1 03/l/91
03/ /91 oncurrence


relays.In addition to identifying
bt


deficiencies
SC:RSIB:DRIS


in the setpoints
EVImbro*
02/08/91 C:RSIB:DRIS


themselves, the NRC has determined
WDLanning*
 
02/19/91 D:DRIS
that licensees
 
are not typically
 
verifying
 
that the magnitude of instrument
 
drift that was assumed in the original setpoint calculation
 
coincides
 
with the magnitude
 
of drift observed in the plant. Licensee can verify the magnitude
 
of instrument
 
drift by trending, (comparing
 
'as found" calibration
 
data to previous 'as left" data). This is particularly
 
important for the degraded grid relay setpoints, which often require very tight calibra-tion tolerance
 
bands, and for which very low drift values are often assumed.This information
 
notice requires no specific action or written response.
 
If you have any questions
 
about the information
 
in this notice, please contact the technical
 
contact listed below or the appropriate
 
NRR project manager.Charles E. Rossi, Director Division of Operational
 
===Events Assessment===
Office of Nuclear Reactor Regulation
 
Technical
 
Contact: Jeffrey B. Jacobson, NRR (301) 492-0996 Attachment:
RPB:ADM TechEd* imJa 03/20/91 P RSIB:DRIS JBdacobson*:t
 
02/08/91 List of Recently Issued NRC Information
 
Notices C:OGCB:UOEA


D:DOEA *See previous c CHBerlinger
BKGrimes*
02/27/91 C:SELB:DST


CERossi 1 03/l/91 03/ /91 oncurrence
FRosa*
 
03/18/91 C:SICB:DST
bt SC:RSIB:DRIS
 
EVImbro*02/08/91 C:RSIB:DRIS
 
WDLanning*
02/19/91 D:DRIS BKGrimes*02/27/91 C:SELB:DST
 
FRosa*03/18/91 C:SICB:DST


SNewberry*
SNewberry*
03/18/91  
03/18/91
; -IN 91-XX January xx, 1991 Inadequate


Setpoint Determinations
;
-
IN 91-XX


and Evaluations
January xx, 1991 Inadequate Setpoint Determinations and Evaluations


Many of the findings identified
Many of the findings identified during recent EDSFIs were related to inadequate


during recent EDSFIs were related to inadequate
setpoint determinations. In order to properly determine an appropriate


setpoint determinations.
instrument setpoint, all associated inaccuracies and tolerances must be


In order to properly determine
accounted for. Useful guidance for determining setpoints is provided by ISA


an appropriate
67.04-1982, "Setpoints for Nuclear Safety-Related Instrumentation used in


instrument
Nuclear Power Plants' which has been endorsed by Regulatory Guide 1.105 Revision 2 - 1986, "Instrument Setpoints for Safety Related Systems". This


setpoint, all associated
guidance is applicable not Just for instrumentation but is also applicable for


inaccuracies
certain relays and other control oriented pieces of equipment.


and tolerances
The setpoint problem has been identified primarily with those instruments in


must be accounted
which the licensee has determined the setpoints as opposed to those setpoints


for. Useful guidance for determining
determined by the NSSS vendor. Those setpoints not contained in the plant


setpoints
technical specifications are also likely to be suspect. During recent EDSFIs, deficiencies in setpoints related to diesel day tank level indicators, diesel


is provided by ISA 67.04-1982, "Setpoints
air start compressor controllers and alarms, invertor low voltage shutdown


for Nuclear Safety-Related
circuitry, degraded grid relays, and diesel overcurrent relays have been


Instrumentation
identified.


used in Nuclear Power Plants' which has been endorsed by Regulatory
In addition to the deficiencies identified in the setpoints themselves, the NRC


Guide 1.105 Revision 2 -1986, "Instrument
has determined that licensees are not typically verifying that the magnitude of


Setpoints
setpoint drift that was assumed in the original setpoint calculation is indeed


for Safety Related Systems".
correct. This verification can be performed by trending, i.e., by comparing


This guidance is applicable
"as found" calibration data to previous "as left" data. This is particularly


not Just for instrumentation
important for the degraded grid setpoints where very tight calibration


but is also applicable
tolerance bands are often required and where very low drift values are often


for certain relays and other control oriented pieces of equipment.
assumed. Failure to evaluate and account for instrument drifts has led to the


The setpoint problem has been identified
operation of equipment outside of acceptable limits which could compromise the


primarily
safety functions of the equipment.


with those instruments
This information notice requires no specific action or written response. If


in which the licensee has determined
you have any questions about the information in this notice, please contact the


the setpoints
technical contact listed below or the appropriate NRR project manager.


as opposed to those setpoints determined
===Charles E. Rossi, Director===
Division of Operational Events Assessment


by the NSSS vendor. Those setpoints
===Office of Nuclear Reactor Regulation===


not contained
===Technical Contact:===


in the plant technical
===Jeffrey B. Jacobson, NRR===
(301) 492-0996 Attachment:


specifications
===List of Recently Issued NRC Information Notices===
*See previous concurrence


are also likely to be suspect. During recent EDSFIs, deficiencies
RPB:ADM


in setpoints
C:OGCB:DOEA


related to diesel day tank level indicators, diesel air start compressor
D:DOEA


controllers
TechEd


and alarms, invertor low voltage shutdown circuitry, degraded grid relays, and diesel overcurrent
CHBerlinger
 
relays have been identified.
 
In addition to the deficiencies
 
identified
 
in the setpoints
 
themselves, the NRC has determined
 
that licensees
 
are not typically
 
verifying
 
that the magnitude
 
of setpoint drift that was assumed in the original setpoint calculation
 
is indeed correct. This verification
 
can be performed
 
by trending, i.e., by comparing"as found" calibration
 
data to previous "as left" data. This is particularly
 
important
 
for the degraded grid setpoints
 
where very tight calibration
 
tolerance
 
bands are often required and where very low drift values are often assumed. Failure to evaluate and account for instrument
 
drifts has led to the operation
 
of equipment
 
outside of acceptable
 
limits which could compromise
 
the safety functions
 
of the equipment.
 
This information
 
notice requires no specific action or written response.
 
If you have any questions
 
about the information
 
in this notice, please contact the technical
 
contact listed below or the appropriate
 
NRR project manager.Charles E. Rossi, Director Division of Operational
 
===Events Assessment===
Office of Nuclear Reactor Regulation


Technical
CERossi


Contact: Jeffrey B. Jacobson, NRR (301) 492-0996 Attachment:
02/ /91  
List of Recently Issued NRC Information
02/ /91  
 
02/ /91 Xrt"
Notices*See previous concurrence
RSIB:DRIS
 
RPB:ADM C:OGCB:DOEA
 
D:DOEA TechEd CHBerlinger
 
CERossi 02/ /91 02/ /91 02/ /91 Xrt" RSIB:DRIS


SC:RSIB:DRIS
SC:RSIB:DRIS


C: S C:S C:SI JBJacobson*:bt
C:  
S


EVImbro* WD ng mes FRoV-rW SNe rry 02/08/91 02/08/91 024 7/91 02/t7/91 "- / 91O/91 IN 91-XX January xx, 1991 Inadequate
C:S


Setpoint Determinations
C:SI


and Evaluations
JBJacobson*:bt EVImbro*
WD


Many of the findings identified
ng


during recent EDSFIs were related to inadequate
mes


setpoint determinations.
FRoV-rW


In order to properly determine
SNe


an appropriate
rry


instrument
02/08/91
02/08/91
024 7/91
02/t7/91 "-
/ 91O/91


setpoint, all associated
IN 91-XX


inaccuracies
January xx, 1991 Inadequate Setpoint Determinations and Evaluations


and tolerances
Many of the findings identified during recent EDSFIs were related to inadequate


must be accounted
setpoint determinations. In order to properly determine an appropriate


for. Guidance for setpoint determinations
instrument setpoint, all associated inaccuracies and tolerances must be


is given in ANSI Standard S67.04-1988, 'Setpoints
accounted for. Guidance for setpoint determinations is given in ANSI Standard


for Nuclear Safety-Related
S67.04-1988, 'Setpoints for Nuclear Safety-Related Instrumentation." This


Instrumentation." This guidance is applicable
guidance is applicable not Just for instrumentation but is also applicable for


not Just for instrumentation
certain relays and other control oriented pieces of equipment.


but is also applicable
The setpoint problem is most prevalent for those instruments in which the


for certain relays and other control oriented pieces of equipment.
licensee has determined the setpoints as opposed to those setpoints determined


The setpoint problem is most prevalent
by the NSSS vendor. Those setpoints not contained in the plant technical


for those instruments
specifications are also likely to be suspect. During recent EDSFIs, defi- ciencies in setpoints related to diesel day tank level indicators, diesel air


in which the licensee has determined
start compressor controllers and alarms, invertor low voltage shutdown


the setpoints
circuitry, degraded grid relays, and diesel overcurrent relays have been


as opposed to those setpoints
identified.


determined
In addition to the deficiencies identified in the setpoints themselves, the NRC


by the NSSS vendor. Those setpoints
has determined that licensees are not typically verifying that the magnitude of


not contained
setpoint drift that was assumed in the original setpoint calculation is indeed


in the plant technical specifications
correct. This verification can be performed by trending, i.e., by comparing


are also likely to be suspect. During recent EDSFIs, defi-ciencies in setpoints
"as found" calibration data to previous "as left" data. This is particularly


related to diesel day tank level indicators, diesel air start compressor
important for the degraded grid rely setpoints where very tight calibration


controllers
tolerance bands are often required and where very low drift values are often


and alarms, invertor low voltage shutdown circuitry, degraded grid relays, and diesel overcurrent
assumed. Failure to evaluate and account for instrument drifts has led to the


relays have been identified.
operation of equipment outside of acceptable limits which could compromise the


In addition to the deficiencies
safety functions of the equipment.


identified
This information notice requires no specific action or written response. If


in the setpoints
you have any questions about the information in this notice, please contact the


themselves, the NRC has determined
technical contact listed below or the appropriate NRR project manager.


that licensees
===Charles E. Rossi, Director===
Division of Operational Events Assessment


are not typically
===Office of Nuclear Reactor Regulation===


verifying
===Technical Contact:===


that the magnitude
===Jeffrey B. Jacobson, NRR===
(301) 492-0996 Attachment: List of Recently Issued NRC Information Notices


of setpoint drift that was assumed in the original setpoint calculation
RPB:ADM


is indeed correct. This verification
C:OGCB:DOEA


can be performed
D:DOEA


by trending, i.e., by comparing"as found" calibration
TechEd


data to previous "as left" data. This is particularly
CHBerlinger


important
CERossi


for the degraded grid rely setpoints
02/ /91
02/ /91
02/ /91 RSIB:
SC:RX


where very tight calibration
RIS


tolerance
C:RSIB:DRIS


bands are often required and where very low drift values are often assumed. Failure to evaluate and account for instrument
D:DRIS


drifts has led to the operation
C:SELB:DST


of equipment
C:SICB:DST
 
outside of acceptable
 
limits which could compromise
 
the safety functions
 
of the equipment.
 
This information
 
notice requires no specific action or written response.
 
If you have any questions


about the information
JBJac 6n:bt EVIm 'J>'
WDLanning


in this notice, please contact the technical
BKGrimes


contact listed below or the appropriate
FRosa
 
NRR project manager.Charles E. Rossi, Director Division of Operational
 
===Events Assessment===
Office of Nuclear Reactor Regulation
 
Technical
 
Contact: Jeffrey B. Jacobson, NRR (301) 492-0996 Attachment:
List of Recently Issued NRC Information
 
Notices RPB:ADM C:OGCB:DOEA
 
D:DOEA TechEd CHBerlinger
 
CERossi 02/ /91 02/ /91 02/ /91 RSIB: SC:RX RIS C:RSIB:DRIS
 
D:DRIS C:SELB:DST
 
C:SICB:DST


JBJac 6n:bt EVIm 'J>' WDLanning
SNewberry


BKGrimes FRosa SNewberry 020 A' 02/djz1 02/ /91 02/ /91 02/ /91 02/ /91}}
020 A'  
02/djz1  
02/ /91  
02/ /91  
02/ /91  
02/ /91}}


{{Information notice-Nav}}
{{Information notice-Nav}}

Latest revision as of 10:17, 16 January 2025

Deficiencies Identifie During Electrical Distribution System Functional Inspections
ML031190636
Person / Time
Site: Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane  
Issue date: 04/15/1991
From: Rossi C
Office of Nuclear Reactor Regulation
To:
References
IN-91-029, NUDOCS 9104090124
Download: ML031190636 (10)
v • d • e


4 A

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C.

20555

April 15, 1991

NRC INFORMATION NOTICE NO. 91-29:

DEFICIENCIES IDENTIFIED DURING ELECTRICAL

DISTRIBUTION SYSTEM FUNCTIONAL INSPECTIONS

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is intended to alert addressees to deficiencies identi- fied during recently performed electrical distribution system functional

inspections (EDSFIs).

It is expected that recipients will review the informa- tion for applicability to their facilities and consider actions, as appropri- ate, to avoid similar problems.

However, suggestions contained in this

information notice do not constitute NRC requirements; therefore, no specific

action or written response is required.

Description of Circumstances

During multidisciplinary inspections, the U.S. Nuclear Regulatory Commission

(NRC) has identified many deficiencies related to tWeelectrical distribution

system. To address these deficiencies, the NRC has developed an inspection to

specifically evaluate the electrical distribution system. During the last

year, the NRC completed eight EDSFIs, performing at least one in each of the

five NRC geographical regions. During these inspections, the staff found

several common deficiencies in the licensees' programs and in the electrical

distribution systems as designed and configured at each plant. These deficien- cies included inadequate ac voltages at the 480 Vac and 120 Vac distribution

levels, inadequate procedures to test circuit breakers, and inadequate determi- nations and evaluations of setpoints.

Discussion:

Inadequate Voltage

During inspections conducted at the San Onofre Nuclear Generating Station

(Inspection Reports 50-361/89-200 and 50-362/89-200), the Susquehanna Steam

Electric Station (Inspection Reports 50-387/90-200 and 50-388/90-200), and the

9104090124

' J

IN 91-29 April 15, 1991 Waterford Steam Electric Station (Inspection Report 50-382/90-23), the staff

found that, under certain conditions, the voltage available at the safety buses

would be inadequate to Operate safety-related loads and associated equipment.

These conditions could occur when the plan~t's electrical distribution systems

were being supplied from an offsite grid that had become degraded but that

continued to supply voltages that remained above the setpoints at which the

degraded grid relays would be activated.

At San Onofre, the numerous voltage drops throughout the system could cause the

voltage to 120 Vaciontactors to drop below the-voltage range for which these

contactors were certified as acceptable by their manufacturers.

To resolve

this problem the licensee has performed testing that established a lower

acceptable voltage range for this equipment.

At Susquehanna, the degraded grid relay setpoint'was'set at 84 percent on the

4160 Yac buses.

Th'i's setpoint could have allowed inadequate voltage to be

-delivered to numerous safety-related loads at both the 480 Vac and 120 Vac

levels. The licensee calculated that setpoints'of at least 93 percent would be

required to ensure adequate voTtage to all safety-related equipment. To

resolve this problem, the lice'isee has raised the setpoints of the degraded

grid relays and has initiated a modification to install 120 Vac regulating

transformers.

At the Waterford nuclear plant, the degraded grid relays were set at

87.5 percent'as sensed on the'4160 Vac buses. :Although this setting was found

to be marginally adequate-'for-equipment connected to the 4160 Vac buses, the

setting was too low to ensure that adequate v6ltage would'be maintained at the

480 Vac and 120 Vac levels. The licensee is 6e4aluating solutions to this

problem and has instituted a procedure- to manually'separate from the grid if

the voltage falls to unacceptable levels but remains above the relay setpoints.

The function of the degraded grid relays is to en'sure that adequate voltage is

available tooperate all Class lE loads at all distribution levels.

In order

to ensure-that all required' Class E 'loads will remain operable during degraded

voltage conditions, some licensees are currently'reanalyzing the basis for the

degraded grid relay setpoints. The new analyses consider all required Class 1E

loads and include the assumption that the voltage on the buses being sensed by

these relays can remain at a level just above the relay setpoints.

Inadequate Circuit Breaker Testing Procedures

During recent EDSFIs ahd previously on other NRC inspections, the staff identi- fied repetitive deficiencies in licensees' programs to test circuit breakers.

These deficiencies included inadequate procedures, inadequate test acceptance

criteria, inadequate test equipment, and inadequate control of testing. At the

Susquehanna plant (Inspection Reports 50-387/90-200 and 50-388/90-200), the

staff found that the licensee was testing dc molded case circuit breakers with

a procedure written for testing ac breakers. The licensee had not established

specific acceptance criteria for the dc breakers.

IN 91-29 April 15, 1991 At the Shearon Harris Nuclear Power Plant (Inspection Report 50-400/90-200),

the staff identified that the licensee was.testing molded case circuit breakers

against National Electrical Manufacturers Association (NEMA),acceptance crite- ria, which were less stringent than the manufacturer's time-current curves for

these breakers. In addition, the staff identified that the licensee was

testing 480 V air circuit breakers with test equipment that applied a test

signal (secondary injection) to the solid state trip units in the circuit

breakers.

Although this method adequately verified that the trip units func- tioned properly, it did not verify that the breaker's current transformer

functioned properly or that the wiring and connectors were adequate between the

current transformer and the solid state trip units. Other licensees have

performed testing by primary current injection or by individually checking each

component of the circuit breaker, including the wiring and connectors to

demonstrate that the circuit breaker functions properly.

Inadequate Determinations and Evaluations of Setpoints

Many of the findings identified during recent EDSFIs were related to inadequate

setpoint determinations. Useful guidance for determining setpoints is provided

by Instrument Society of America Standard 67.04-1982, "Setpoints for Nuclear

Safety-Related Instrumentation used in Nuclear Power Plants," which the NRC

staff has endorsed by Regulatory Guide 1.105 Revision 2 -

1986, "Instrument

Setpoints for Safety-Related Systems." This guidance applies both to process

instrumentation and, in part, to certain relays that perform a safety function.

Some licensees have operated equipment outside of acceptable limits because

they did not determine proper setpoints and did not evaluate and account for

instrument drift. Operating the equipment under these conditions could

compromise the safety functions of the equipment. The staff has identified

these circumstances primarily for those instruments in which the licensee has

determined the setpoints as opposed to those instruments for which the

setpoints were determined by the architect/engineer or the nuclear safety

system supplier. Those setpoints not contained in the plant technical specifi- cations were also more frequently found to be deficient. During recent EDSFIs, the staff identified deficiencies in setpoints for diesel day tank level

indicators, diesel air start compressor controllers and alarms, inverter low

voltage shutdown circuitry, degraded grid relays, and diesel overcurrent

relays.

In addition to identifying deficiencies in the setpoints themselves, the NRC

has determined that not all the licensees are typically verifying that the

magnitude of instrument drift that was assumed in the original setpoint calcu- lation coincides with the magnitude of drift observed in the plant. Some

licensees have corrected this deficiency by verifying the magnitude of instru- ment drift by trending, (comparing "as found" calibration data to previous "as

left" data). This is particularly important for the degraded grid relay

setpoints, which often require very tight calibration tolerance bands, and for

which very low drift values are often assumed.

v- IN 91-29 April 15, 1991 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, eirector

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment: List of Recently Issued NRC Information Notices

i

Attachment 1

IN 91-29

April 15, 1991 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

91-28

91-27

89-90,

Supp. 1

91-26

91-25

91-24

91-23

Cracking in Feedwater

System Piping

Incorrect Rotation of

Positive Displacement Pump

Pressurizer Safety Valve

Lift Setpoint Shift

Potential Nonconservative

Errors in the Working Format

Hansen-Roach Cross-Section

Set Provided with The Keno

and Scale Codes

Commercial-Grade Structural

Framing Components Supplied

As Nuclear Safety-Related

Equipment

Recent Operating Experience

Involving Reactor Operation

Without A Licensed Reactor

Operator or Senior Reactor

Operator Present in the

Control Room

Accidental Radiation Over- exposures to Personnel Due to

Industrial Radiography Acces- sory Equipment Malfunctions

04/15/91

All holders of OLs or

CPs for pressurized

water reactors (PWRs).

04/10/91

All holders of OLs or

CPs for nuclear power

reactors.

04/10/91

All holders of OLs or

CPs for nuclear power

reactors.

04/02/91

All fuel cycle licensees

and other licensees, in- cluding all holders of

operating licenses for

nuclear power reactors, who use physics codes to

support criticality

safety in the use of

fissile material.

04/01/91

All holders of OLs or

CPs for nuclear power

reactors.

03/26/91

All holders of OLs or

CPs for nuclear power, test, and research re- actors, and all Part 55 licensed operators.

03/26/91

All Nuclear Regulatory

Commission (NRC) licens- ees authorized to use

sealed sources for indus- trial radiography.

OL = Operating License

CP = Construction Permit

IN 91-29 April 15, 1991 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

O6ginal agen& by

Charles E. Ross!

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment:

List of Recently Issued NRC Information Notices

  • SEE PREVIOUS

04/ fI9 OGC :DOEA: RR

PCWen

04/

/91

CONCURRENCES

  • C/OGCB:DOEA:NRR*RPB:ADM
  • C/SICB:DST:NRR

CHBerlinger

TechEd

SNewberry

04/08/91

03/20/91

03/18/91

  • RSIB:DRIS:NRR *SC/RSIB:DRIS:NRR*C/RSIB:DRIS:NRR

JBJacobson:bt

EVImbro

WDLanning

02/08/91

02/08/91

02/19/91

  • C/SELB:DST:NRR

FRosa

03/18/91

  • D/DRIS:NRR

BKGrimes

02/27/91

  • - I

IN 91-XX

April xx, 1991 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996

List of Recently Issued NRC Information Notices

Attachment:

  • SEE PREVIOUS CONCURRENCES
  • C/SICB:DST:NRR

D/DOEA:NRR

C/OGCB:DO

T*RPB:Ad

SNewBerry

CERossi Y-

CHBerling rjw TechEd

04/ /91

04/8/91

03/20/91

03/18/91

,c

CB:DOEA:NRR *RSIB:DRIS:NRR *SC/RSIB:DRIS:NRR*C/RSIB:DRISNRR

4CvPvWen

JBJacobson:bt

EVImbro

WMLanning

04/cl/91

02/08/91

02/08/91

02/19/91

  • C/SELB:DST:NRR

FRosa

03/18/91

  • D/DRIS:NRR

BKGrimes

02/27/91

IN 91-XX

March xx, 1991 Inadequate Determinations and Evaluations of Setpoints

Many of the findings identified during recent EDSFIs related to inadequate

setpoint determinations. Useful guidance for determining setpoints is provided

by Instrument Society of America Standard 67.04-1982, "Setpoints for Nuclear

Safety-Related Instrumentation used in Nuclear Power Plants," which the NRC

staff has endorsed by Regulatory Guide 1.105 Revision 2 - 1986, "Instrument

Setpoints for Safety-Related Systems." This guidance applies both to process

instrumentation and, in part, to certain relays that perform a safety function.

Licensees have operated equipment outside of acceptable limits because they did

not determine proper setpoints and did not evaluate and account for instrument

drifts. Operating the equipment under these conditions could compromise the

safety functions of the equipment. The staff has identified these circum- stances primarily for those instruments in which the licensee has determined

the setpoints as opposed to those instruments for which the setpoints were

determined by the architect/engineer or the nuclear safety system supplier.

Those setpoints not contained in the plant technical specifications were also

more frequently found to be deficient. During recent EDSFIs, the staff

identified deficiencies in setpoints for diesel day tank level indicators, diesel air start compressor controllers and alarms, inverter low voltage

shutdown circuitry, degraded grid relays, and diesel overcurrent relays.

In addition to identifying deficiencies in the setpoints themselves, the NRC

has determined that licensees are not typically verifying that the magnitude

of instrument drift that was assumed in the original setpoint calculation

coincides with the magnitude of drift observed in the plant.

Licensee can

verify the magnitude of instrument drift by trending, (comparing 'as found"

calibration data to previous 'as left" data). This is particularly important

for the degraded grid relay setpoints, which often require very tight calibra- tion tolerance bands, and for which very low drift values are often assumed.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment:

RPB:ADM

TechEd* imJa

03/20/91 P

RSIB:DRIS

JBdacobson*:t

02/08/91

List of Recently Issued NRC Information Notices

C:OGCB:UOEA

D:DOEA

  • See previous c

CHBerlinger

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1 03/l/91

03/ /91 oncurrence

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02/08/91 C:RSIB:DRIS

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02/19/91 D:DRIS

BKGrimes*

02/27/91 C:SELB:DST

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03/18/91 C:SICB:DST

SNewberry*

03/18/91

-

IN 91-XX

January xx, 1991 Inadequate Setpoint Determinations and Evaluations

Many of the findings identified during recent EDSFIs were related to inadequate

setpoint determinations. In order to properly determine an appropriate

instrument setpoint, all associated inaccuracies and tolerances must be

accounted for. Useful guidance for determining setpoints is provided by ISA

67.04-1982, "Setpoints for Nuclear Safety-Related Instrumentation used in

Nuclear Power Plants' which has been endorsed by Regulatory Guide 1.105 Revision 2 - 1986, "Instrument Setpoints for Safety Related Systems". This

guidance is applicable not Just for instrumentation but is also applicable for

certain relays and other control oriented pieces of equipment.

The setpoint problem has been identified primarily with those instruments in

which the licensee has determined the setpoints as opposed to those setpoints

determined by the NSSS vendor. Those setpoints not contained in the plant

technical specifications are also likely to be suspect. During recent EDSFIs, deficiencies in setpoints related to diesel day tank level indicators, diesel

air start compressor controllers and alarms, invertor low voltage shutdown

circuitry, degraded grid relays, and diesel overcurrent relays have been

identified.

In addition to the deficiencies identified in the setpoints themselves, the NRC

has determined that licensees are not typically verifying that the magnitude of

setpoint drift that was assumed in the original setpoint calculation is indeed

correct. This verification can be performed by trending, i.e., by comparing

"as found" calibration data to previous "as left" data. This is particularly

important for the degraded grid setpoints where very tight calibration

tolerance bands are often required and where very low drift values are often

assumed. Failure to evaluate and account for instrument drifts has led to the

operation of equipment outside of acceptable limits which could compromise the

safety functions of the equipment.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment:

List of Recently Issued NRC Information Notices

  • See previous concurrence

RPB:ADM

C:OGCB:DOEA

D:DOEA

TechEd

CHBerlinger

CERossi

02/ /91

02/ /91

02/ /91 Xrt"

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IN 91-XX

January xx, 1991 Inadequate Setpoint Determinations and Evaluations

Many of the findings identified during recent EDSFIs were related to inadequate

setpoint determinations. In order to properly determine an appropriate

instrument setpoint, all associated inaccuracies and tolerances must be

accounted for. Guidance for setpoint determinations is given in ANSI Standard

S67.04-1988, 'Setpoints for Nuclear Safety-Related Instrumentation." This

guidance is applicable not Just for instrumentation but is also applicable for

certain relays and other control oriented pieces of equipment.

The setpoint problem is most prevalent for those instruments in which the

licensee has determined the setpoints as opposed to those setpoints determined

by the NSSS vendor. Those setpoints not contained in the plant technical

specifications are also likely to be suspect. During recent EDSFIs, defi- ciencies in setpoints related to diesel day tank level indicators, diesel air

start compressor controllers and alarms, invertor low voltage shutdown

circuitry, degraded grid relays, and diesel overcurrent relays have been

identified.

In addition to the deficiencies identified in the setpoints themselves, the NRC

has determined that licensees are not typically verifying that the magnitude of

setpoint drift that was assumed in the original setpoint calculation is indeed

correct. This verification can be performed by trending, i.e., by comparing

"as found" calibration data to previous "as left" data. This is particularly

important for the degraded grid rely setpoints where very tight calibration

tolerance bands are often required and where very low drift values are often

assumed. Failure to evaluate and account for instrument drifts has led to the

operation of equipment outside of acceptable limits which could compromise the

safety functions of the equipment.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment: List of Recently Issued NRC Information Notices

RPB:ADM

C:OGCB:DOEA

D:DOEA

TechEd

CHBerlinger

CERossi

02/ /91

02/ /91

02/ /91 RSIB:

SC:RX

RIS

C:RSIB:DRIS

D:DRIS

C:SELB:DST

C:SICB:DST

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WDLanning

BKGrimes

FRosa

SNewberry

020 A'

02/djz1

02/ /91

02/ /91

02/ /91

02/ /91


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